Wetland Biodiversity and Water Quality Surveys, Violetvale Station Brendan C. Ebner and James A. Donaldson Report No. 15/78 December 2015 Wetland Biodiversity and Water Quality Surveys, Violetvale Station A Report for Cape York NRM Report No. 15/78 December 2015 Prepared by Brendan C. Ebner and James A. Donaldson Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER) James Cook University Townsville Phone : (07) 4781 4262 Email: [email protected] Web: www.jcu.edu.au/tropwater/ Information should be cited as: Ebner BC & Donaldson JA (2015), ‘Wetland Biodiversity and Water Quality Surveys, Violetvale Station’, Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER) Publication 15/78, James Cook University, Cairns, 22 pp. For further information contact: Brendan Ebner Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER) James Cook University [email protected] PO Box 780, 47 Maunds Road , Atherton QLD 4883 This publication has been compiled by the Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER), James Cook University. © James Cook University, 2015. Except as permitted by the Copyright Act 1968, no part of the work may in any form or by any electronic, mechanical, photocopying, recording, or any other means be reproduced, stored in a retrieval system or be broadcast or transmitted without the prior written permission of TropWATER. The information contained herein is subject to change without notice. The copyright owner shall not be liable for technical or other errors or omissions contained herein. The reader/user accepts all risks and responsibility for losses, damages, costs and other consequences resulting directly or indirectly from using this information. Enquiries about reproduction, including downloading or printing the web version, should be directed to [email protected]. Acknowledgments: We would like to gratefully acknowledge the key field and logistical assistance of Michael Goddard, Cape York NRM. Peta-Marie Standley (CYNRM) organised the project and James and Nikki Collins, provided access and accommodation at the beautiful Violetvale Station. Nathan Waltham assisted with freshwater crab identification and Mark Kennard provided excerpts from his Master’s thesis at short notice. Aaron Davis provided a review of this report. Field work was conducted under Queensland General Fisheries Permit 151660 and James Cook University Animal Ethics Permit A2178. Violetvale wetland surveys – TropWATER Report no. 15/78 2015 EXECUTIVE SUMMARY This report documents the findings from a five day field trip to Violetvale Station in the Normanby drainage basin of eastern Cape York. In anticipation of large scale fencing-off of wetlands, the main focus of this study was to document aquatic biodiversity, primarily fishes, and to a lesser extent crustaceans, aquatic reptiles and waterbirds. The study also served to provide some context in terms of basic water quality records from the wetlands on the property. Surveys targeted four large wetlands across Violetvale Station in the Saltwater Creek catchment, but also included opportunistic surveys at a further seven sites (comprising small in-channel waterholes and floodplain wetlands) on the property. Across the eleven sites surveyed, a total of 19 fish, 2 aquatic reptiles, 8 aquatic macroinvertebrate and 16 waterbird species were observed. Estuarine crocodiles were recorded from each of the large wetlands, with a maximum count of two individuals in the most downstream of the large wetlands. Juvenile barramundi were caught in low numbers and in good condition at three of four main wetlands. Turtles were not caught at any sites, although the shell of a turtle was found on an earlier pilot study. Large aquatic beetles (Dysticids) were found in high abundance in all four large wetlands. By way of relevant observations, wild pigs were observed at wetland edges and feral cattle were occupying edge and wetland habitat. Signs of trampling and diggings from these mammals were evident around the edges of the large wetlands. There is scope for fencing stock and pigs from these wetlands and determining potential shifts in aquatic and semi-aquatic (e.g. turtle) biodiversity using this report as a baseline. Page i Violetvale wetland surveys – TropWATER Report no. 15/78 2015 TABLE OF CONTENTS EXECUTIVE SUMMARY ............................................................................................................................ i 1 INTRODUCTION ................................................................................................................................. 3 2 METHODS ......................................................................................................................................... 4 2.1 Study sites ................................................................................................................................. 4 2.2.1 Netting ........................................................................................................................ 6 2.2.2 Spot lighting ................................................................................................................ 7 2.2.3 Baited Remote Underwater Video Stations (BRUVS) ..................................................... 7 2.2.4 Bait traps ..................................................................................................................... 8 2.2.5 Wetland birds .............................................................................................................. 8 2.3 Water quality sampling .............................................................................................................. 9 3 RESULTS .......................................................................................................................................... 10 3.1 Wetland fauna survey .............................................................................................................. 10 3.2 Water quality sampling ............................................................................................................ 10 4 DISCUSSION .................................................................................................................................... 17 5 REFERENCES .................................................................................................................................... 21 A APPENDICES .................................................................................................................................... 23 A.1 Survey effort applied at each site ............................................................................................. 23 A.2 GPS locations for each site surveyed ......................................................................................... 23 A.3 X-ray image of skeletal structure of Anguilla specimens retained from the study. A represents Anguilla cf. obscura, whereas, B represents Anguilla reinhardtii. ...................................................... 24 Page ii Violetvale wetland surveys – TropWATER Report no. 15/78 2015 1 INTRODUCTION Pastoral grazing represents a major contributor to the economy of northern Australia and is central to large scale food production for humans (McKeon et al. 1990, Bortolussi et al. 2005, MacLeod & McIvor 2006). However, these large mammals also influence catchment processes directly in terms of plant composition and primary production, nutrient and moisture uptake and release, soil erosion and landscape drainage, and indirectly by shaping biotic community composition. In this regard there can be negative impacts on native ecosystems including streams, wetlands and aquatic biota (Dodds et al. 2015) and balancing production in a sustainable manner is not easily achieved (MacLeod & McIvor 2006). Wetlands are ecosystems that support high levels of biodiversity and perform essential ecosystem services. Importantly, they serve as nursery and refuge habitat for commercially, culturally and recreationally significant fish species including barramundi, sleepy cod and tarpon. The wetlands of Cape York are of high conservation value and provide habitat for a large number of plant and animal species (EHP, 2012). Some of the wetland systems along the expansive Eastern Cape York Peninsula of Australia have been surveyed for fishes (e.g. Herbert & Peters 1995, Kennard 1995, Pusey et al. 2000). However, riverine and wetland fish communities of Eastern Cape York have not received the level of survey effort afforded in more southern parts of the east coast of Australia, undoubtedly in part due to the relative inaccessibility of the most northerly systems in Queensland. This lack of a strong research base or monitoring of fish and aquatic ecosystems inhibits the sustainable management of ecosystems in the region, including the vast wetland complexes typifying the greater Laura- Normanby catchment. These wetland ecosystems are vulnerable to degradation by feral herbivores such as cattle, pigs and horses as well as invasion by semi-aquatic and aquatic weeds (e.g. Doupé et al., 2009). It is important to establish a baseline inventory of species inhabiting these wetlands to monitor changes associated with management actions such as destocking, exclusion fencing and weed removal on cattle properties and in national parks. Arguably, the large national parks and cattle properties of the Cape provide the most pragmatic unit for environmental management in view of irregular government funding.